1. Field of the Invention
The present invention relates to an electrode assembly and a lithium rechargeable battery using the same. In particular, the present invention relates to an electrode assembly comprising an electrode tab or an electrode plate substrate that has an identification mark formed thereon and a lithium rechargeable battery using the same.
2. Description of the Prior Art
With the recent advancement of electronic technologies, particularly portable electronic devices, rechargeable batteries that are used to power these devices have also improved considerably. Lithium rechargeable batteries are some of the most widely-used batteries because of their excellent characteristics including high operating voltage, long service life, and high energy density.
In the lithium rechargeable batteries, positive electrodes and negative electrodes comprise materials that enable lithium ions to be reversibly inserted into and separated from them. The space between the positive electrode and the negative electrode is filled with an organic electrolyte or a polymer electrolyte. As the lithium ions are inserted into and separated from the positive electrode and the negative electrode, oxidation and reduction reactions occurring at the electrodes generate electrical energy.
In general, the bare cell of a lithium rechargeable battery is formed by placing an electrode assembly comprised of a positive electrode, a negative electrode, and a separator into a can. The can may comprise aluminum or an aluminum alloy. The can is sealed with a cap assembly and an electrolyte is injected into the can. Aluminum or an aluminum alloy may be used to form the can because they are lightweight and corrosion resistant even at high operating voltages during a long operating time. This reduces the overall weight of the battery.
The bare cell generally comprises an electrode terminal that is positioned on top of the bare cell to insulate it from its surroundings. The electrode terminal is coupled with an electrode of the electrode assembly in the bare cell and constitutes either the positive terminal or the negative terminal of the battery. The can itself has the opposite polarity of the electrode terminal.
Referring to FIG. 1, a rectangular-type lithium rechargeable battery 10 according to the prior art includes a can 11, an electrode assembly 12 contained in the can 11, and a cap assembly 100 that is coupled to the can 11.
The can 11 is a rectangular-type case that is made of metallic material. The electrode assembly 12 is formed by laminating a positive electrode plate 13, a separator 14, and a negative electrode plate 15 and winding them into a roll. The electrode assembly 12 is contained in the can 11. The positive electrode tab 16 and negative electrode tab 17 are drawn from the positive electrode plate 13 and negative electrode plate 15, respectively.
The cap assembly 100 includes a cap plate 110 that is coupled to the top of the can 11 and an electrode terminal 130 that is inserted into a terminal through-hole 111 that is formed at the center of the cap plate 110. The cap assembly further includes an insulation plate 140 that is positioned on the lower surface of the cap plate 110 and a terminal plate 150 that is positioned on the lower surface of the insulation plate 140 while being coupled to the electrode terminal 130. A cylindrical gasket 120 is positioned on the outer surface of the electrode terminal 130 to insulate between the electrode terminal and the cap plate 110.
The cap plate 110 has an electrolyte injection hole 112 that is formed therein to provide a passage through which an electrolyte can be injected into the can 11. A ball 160 is coupled with the electrolyte injection hole 112 to seal it.
The positive electrode tab 16 is coupled with the bottom surface of the cap plate 110 and the negative electrode tab 17 is coupled with the electrode terminal 130 via the terminal plate 150. The connection positions of the positive electrode tab 16 and the negative electrode tab 17 may be switched. An insulation tape 18 is wound around a portion through which the positive electrode tab 16 and the negative electrode tab 17 are drawn from the electrode assembly 12 to prevent a short circuit between the positive electrode plate 13 and negative electrode plate 15. The can 11 has an insulation case 30 that is positioned on top of the electrode assembly 12 to insulate between the electrode assembly 12 and the cap assembly 100.
Since batteries store energy, they have the potential to release a large amount of energy. For example, rechargeable batteries accumulate a large amount of energy when they have been charged or during a charging process where they are supplied with energy from other energy source. If any malfunction such as an internal short circuit occurs in the rechargeable batteries during such a process, the accumulated energy may be released quickly and cause a safety problem such as fire or explosion.
Lithium rechargeable batteries are equipped with a safety device to avoid fire or an explosion caused by a malfunction in the batteries when they have been charged or during the charging process. For example, a protective circuit senses abnormal current or voltage and interrupts the flow of current. Other safety devices include a bimetal and a positive temperature coefficient device which is actuated by overheating caused by abnormal currents.
In spite of these precautions, almost all components of batteries are damaged by heat in the event of a fire or other damage to the batteries, which makes it difficult to analyze the cause.